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Choudhury D, et al.

1.4.2 Drug Discovery and Drug Development an intelligent assembly of highly deformable materials
that can be activated by an external stimulus to generate
Bioprinting can advance pharmaceutics under four desired motions [50,51] . Bashir et al. first conceptualised
[52]
different broad categories [38] : (a) Drug delivery (b) the notion of 3D printed “bio-bots” by introducing a
Drug screening (c) Microarrays and high-throughput class of miniaturized walking biological machines,
screenings and (d) Absorption, distribution, metabolism powered by beating cardiac cells. Through precise
and excretion (ADME) assays. Compared to other patterning of cell-laden hydrogels, it is possible to “build”
in vitro models, 3D printed human tissues have robots that are powered by cells.
better spatial control of cells, in vivo-like tissue
microarchitecture, scalability, easier handling, co-culture 1.4.5 Other Emerging Applications
capability, cell-cell and cell-matrix interactions and low Another upcoming application for bioprinting lies in the
[2]
risk of cross-contaminations . Bioprinting potentially consumer product domain. AM has recently emerged
can also ensure controlled delivery of growth factors as a promising strategy for designing food materials
and possibly genes, an important consideration for with complex geometry, detailed patterning, and
longer tissue cultivation [39] . Additionally, these printed customized nutritional value . One such revolutionary
[53]
constructs should be open to complicated phenotypic approach has been the production of tissue engineered
assays used inside a person including biochemistry, meat products through drop-on-demand deposition.
histology and various ‘omics’ methods [40] . The co- Researchers at the University of Missouri–Columbia
printing technology of multiple materials facilitates even have manipulated AM-based tissue engineering for the
closer replication of cellular microenvironment, opening development of comestible food products as an excellent
novel approaches for drug screening. To date, simplified source of protein [54] . Their patents have primarily
[43]
in vitro models of liver [31,32,41,42] and kidney have been focused on initiating an alternate technology to meet the
successfully fabricated using bioprinting. growing demand for consumable meat, which so far has
1.4.3 Disease Modelling been exclusively catered by the overburdened livestock
industry [54,55] .
The premise of modelling disease in vitro is to get In an interesting study, Schroeder et al. [56] made a
the diseased model as similar to that in the actual softer artificial electric organ (power source) by getting
human body and bioprinting can essentially advance inspired from an electric eel. The construct was made
this research. One example is the cancer metastasis up of gradients of ions sandwiched between tiny
process; the mechanical properties (such as stiffness) polyacrylamide hydrogel compartments which were
and composition of a tumour microenvironment often bounded by a repeating sequence of cation- and anion-
undergo quick changes [44,45] , making it challenging selective hydrogel membranes. This electric organ is
to diagnose and treat. Bioprinting can enable the soft, transparent and flexible in comparison to traditional
fabrication of various structural aspects of a tumour batteries. In future, such artificial electric organs could
thereby creating a realistic tumour microenvironment potentially power advanced implant materials such as
with heterogeneous cells and orders of complexity pacemakers and implantable sensors etc.
complete with vasculature [40,45] . To date, bioprinting Green bioprinting [57] is defined as an AM approach
has been employed to create blood vessels of different which involves processing of cells from the plant
diameters to study cancer cell migration [46] as well as kingdom for studying secondary metabolites production
uniform tumour spheroids with hollow necrotic cores . and monitoring methods. Plant bioprinting can also
[47]
The cardiovascular disorder is another prevalent modern potentially revolutionize many applications like,
life-style dependent disease which can be modelled production of plant-based materials from printed tissues,
[48]
using bioprinting . chimeric grafting, in situ/in vivo bioprinting for repairing
[58]
tissues and printing designer plant-based food .
1.4.4 Bio-hybrid Robotics
In recent times, there has been a gradual shift towards 2. commercialization of 3D Bioprinting
technology
[49]
soft robotics from the conventional one . Re searchers
have been cautiously inching towards secundum The expanded applications of bioprinting have driven
naturam (according to nature) for a better understanding the development of bioprinting processes as well as
of the intricate organization in living beings, and their platforms over the last few years (Figure 3). Many
[4]
subsequent biomimicry . This interest germinates new companies have emerged to exploit this upcoming
from the desire to tackle more complex, unpredictable industry, and there are three key areas/business models
environments, which demands higher order of here: (a) directly selling the bioprinters, (b) providing
mechanical intelligence. Hybrid bio-bots are defined as contractual bioprinting services and (c) directly entering

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